An example of a known MOS imager is described in "A solid state color video camera with a horizontal read out MOS imager" (IEEE Transactions on Consumer Electronics, vol. CE-32, No. 3, August 1986). An arrangement of four color filters as described in this article shown in FIG. 16 of the accompanying drawings. Colors of filters covering photodiodes are white (W), green (G), cyan (Cy) and yellow (Ye). The term (i,j) denotes a location of a photodiode at the j-th column and in the i-th row of a matrix array of photodiodes. photoelectric charges accumulated on the photodiodes covered by the filters W, G, Cy and Ye are derived from output terminals 111-114, respectively. The electric charges from photodiodes at two adjacent rows are processed at the same time. This process is sequentially performed line by line in the scan of a display picture. For instance, in the first field, elements (1,1) and (2,1), elements (1,2) and (2,2), elements (1,3) and (2,3), . . . are scanned during a first horizontal period, then elements (3,1) and (4,1), elements (3,2) and (4,2), elements (3,3) and (4,3), . . . are scanned during the second horizontal period, . . . After the scanning of the first field is finished, the scanning of the second field is started. In the second field, elements (2,1) and (3,1), elements (2,2) and (3,2), elements (2,3) and (3,3), . . . are during a first horizontal period, then elements (4,1) and (5,1), elements (4,2) and (5,2), elements (4,3) and (5,3), . . . are scanned during the second horizontal period, . . . Thus, an interlace scan is performed by reading out two-rows-at-a-time. A CCD imager performing an interlace scan by reading out two-rows-at-a-time is disclosed in "A CCD image sensor with parallel-serial transfer conversion circuits" (1984 National Convention Record of the Institute of Television Engineers of Japan).
In previous video cameras with solid state imagers, a zoom feature has not been considered, since the zoom feature requires the video cameras to be provided with an optical mechanism or a picture memory from which pixel (picture element) data is read out with a slower rate of scanning. The optical mechanism makes the video camera heavier and it is not suitable for a rapid zoom operation. On the other hand, an example of an electrical zoom with a memory is disclosed in Japanese laid open application No. 166279/1986; however, the picture resolution in the disclosed device is undesirable since the same pixel data is read out twice in the horizontal and vertical directions (same pixel data is used four times) to create a picture twice as large, i.e. a zoom at a ratio of 2-to-1.
It is possible to improve the resolution in the horizontal direction of a reproduced (display) picture, since it is possible to provide the photodiodes with a high density in the horizontal direction. However, it is difficult to provide the photodiodes with a high density in the vertical direction, since the density in the vertical direction depends on the density of the scan lines of the reproduced picture.